• 10.4 baseline — 0.6 × season 10.4 (8 gm) + 0.4 × last 8 10.4
• −0.6 opponent leak — they concede 200.3/game vs a 213.6 league average
• +0.6 at this ground — averages 11 there (5 gm)

Derived, not measured — plain arithmetic over his real games, shown in full. Adjustments can overlap (a game at this ground can also be a wet one); they add simply, and this note is the admission. Round 1: 21 — far outside his usual range; kept in the average, not smoothed away.